Fluid dispensing gun



March 23, 1965 M. G. BUNDY 3,174,650

' FLUID DISPENSING GUN Filed Aug. 27. 1962 5 Sheets-Sheet 1 /20INVENTOR. Maurice 6. Bandy Arrow/5%.

March 23, 1965 M. G. BUNDY 3,174,660

FLUID DISPENSING GUN Filed Aug. 27, 1962 3 Sheets-Sheet 2 INVENTOR.Maurice 6. Bundy I BY M. G. BUNDY FLUID DISPENSING GUN 3 Sheets-Sheet 3INVENTOR. Maurice 6. Bandy March 23, 1965 Filed Aug. 27, 1962 UnitedStates Patent 3,174,660 FLUID DISRENSING GUN Maurice G. Bandy, Kansasfity, Hans, assignor to The Industrial Fumigant (10., Kansas (Sity, Mo.,a corporation of Iliinois Filed Aug. 27, 1962, Ser. No. 219,511 7(Ilairns. (Cl. ZZZ-424.5)

This invention relates to a fluid dispensing gun, and more particularly,to such a gun used for applying controlled dosages of fumigant materialto products as the same pass through milling machinery and equipment ofa related nature.

It is the most important object of this invention to provide a fluiddispensing gun which can be used in the application of fumigants,insecticides and the like, and which gun automatically delivers apredetermined amount of the fluid material to the area to be treated.

It is a yet further object of this invention to provide a fluiddispensing gun which is adapted to receive fluid under pressure, andwhich gun has therewithin means for regulating the pressure of the fluidwithin the gun, such means taking the form of a floating valve andassociated diaphragm disposed within the gun and in the path of thefluid entering the gun.

It is a yet further object of this invention to provide a fluiddispensing gun which has an outer housing and an inner casing whichcooperate to define a fluid receiving chamber, the inner casing definingan air chamber, there being a diaphragm separating one end of the airchamber from the fluid chamber, there also being means associated withsaid diaphragm and the fluid chamber which serve to control the dosagedelivered by the gun by controlling the length of time which the gunremains open upon an initial actuation thereof.

A yet further object is to provide a fluid dispensing gun which has afluid chamber, there being a fluid outlet spout in communication withsaid chamber and suitable mechanism carried by the gun for opening avalve of the outlet spout whereby to deliver therethrough a controlledamount of fluid fumigant or the like.

Another object of this invention is to provide a fluid dispensing gunwhich is positive in all respects of its operation, and which will notdrip or leak fluid subsequent to the closing of the valve in the fluiddelivery spout.

Still another object of the invention is to provide a fluid dispensinggun which delivers a controlled dosage of fumigant to the selectedproducts, the means for controlling the dosage delivered by the gunbeing a part of the gun itself and thereby rendering unnecessary,controls disposed at a remote position for controlling the dosagedelivered by the gun.

A yet further aim is to provide a liquid dispensing gun which willhandle all known conventional and standard fluid fumigants, which islightweight and compact, making the same easy to handle, and which gunmay be fully controlled as to its operation by the operator thereof.

Other objects of this invention include details of construction whichwill become apparent from the following specification and accompanyingdrawings, wherein:

FIGURE 1 is a side elevational view of the liquid dispensing gun;

FIG. 2A is an enlarged, fragmentary, sectional view of the gun showingthe same prior to the delivery of fluid thereinto;

FIG. 2B is an enlarged, fragmentary, sectional view of the spout of thegun showing the same in a condition comparable to the other componentsshown in FIG. 2A;

FIG. 3 is a sectional view taken on line 3-3 of FIG. 2A;

FIG. 4A is an enlarged, fragmentary, sectional view of 3,l74,66 PatentedMar. 23, 1965 the gun showing the same at the moment the trigger hasbeen pulled to commence delivery of liquid;

FIG. 4B is an enlarged, fragmentary, sectional view of the spout of thegun showing the same in a delivery condition corresponding to the othercomponents as shown in FIG. 4A;

FIG. 5 is a sectional view taken on line 55 of FIG. 3;

FIG. 6 is a sectional view taken on line 66 of FIG. 4A;

FIG. 7 is a sectional view taken on line 7-7 of FIG. 4B; and

FIG. 8 is a rear elevational view of: the closure member.

The present fluid dispensing gun broadly designated by the numeral 10 isintended for use in the application of liquid fumigants and the likewhich are used in controlling pests and insects in flour mills and otherareas where grain is milled or processed. It is desirable in suchapplication of fumigants and the like to deliver to the portions of thegrain to be treated, a controlled dosage of fumigant whereby the milledproduct will not become over-saturated, but yet will be treated with asufficient amount of fumigant to achieve the desired result.

Thus, the gun 10 is adapted to be coupled to one end of a main supplyline 12 which is coupled with a source of fluid fumigant under pressure,there normally being a main supply valve interposed in line 12 wherebyto control the delivery of the fluid therethrough.

For purposes of illustration, the pressure in line 12 will be describedas being at a rate of 40 pounds, although it will be appreciated thatany sutflcient pressure may be utilized to force fluid through line 12and into the gun 1'0.

Gun 10 includes a housing 14 disposed within a cover 15, said cover 15having a configuration as shown in FIG. 1 of the drawings whereby togive the gun a pistol-like appearance. Gun 10 also includes a trigger 16and a fluid delivery spout 18.

Furnigant fluid is delivered into the interior of housing 14 by line 12and thence through the apparatus hereinafter described whereby itsubsequently is delivered to the milled product or the like through theoutlet spout 18. Housing 14 receives the fluid through a first deliverypassage 20 which is in communication with an inlet supply port 22 towhich line 12 is connected, the fluid passing through passage 26 andthen entering the interior of housing 14 and substantially filling thesame, with the major exception of an air chamber 24, which air chamber24 is primarily defined by a casing 26 which has a piston 23reciprocably disposed therewithin, the casing 26 being generallycylindrical in configuration and being closed at one end by a diaphragm,hereinafter described in detail, and at the other end by a sealing ring32 whereby to prevent the entrance of the fluid into the air chamber 24.

Casing 26 and housing 14 cooperate to define a main fluid-receivingchamber 34 which surrounds the casing 26 and also extends forwardlythereof, viewing FIGS. 2A and 4A, whereby to also surround a toggleassembly broadly designated as 36, the main fluid-receiving chamber 34also extending along the barrel 38 and spout 13 of the gun It) and intosurrounding relationship with a valve rod 40 which carries means closingthe front end of chamber 34. The rear end of chamber 34 is closed by adiaphragm 46 which is suitably held, adjacent its marginal edges, by aclosure member 48 which is threaded onto the rear portion of the housing14 as illustrated in FIGS. 2A and 4A.

Closure member 48 also retains therewithin a coil spring 56 which hasone end thereof bearing against an adjustment screw 52, the other end ofspring 50 bearing against a plate 54, which plate overlies the diaphragm46. The closure member 43 defines, on one side of diaphragm 46, thatbeing the left or rear side thereof viewing FIG. 2A,

an air chamber 56, no fluid being allowed to enter this chamber as aresult of the provision of diaphragm 46, chamber 56 containing air underatmospheric pressure.

A regulator valve broadly designated as 58, is coupled with diaphragm 46by a main shaft 60, the diaphragm 46 being in surrounding relationshipto said shaft 60 and secured thereto as a result of being clampedbetween plate 54 and a plate 62 carried by shaft 60 on the side ofdiaphragm 46 opposite to that upon which plate 54 is disposed. V

Shaft 60 also has formed thereon, in surrounding relationship thereto,an outwardly extending ring 64, which ring 64 has a beveled surfacethereon whereby the same may seat upon a shoulder 66 to effect closingof the valve 58, it being apparent that shaft 60 of valve 8 isreciprocable in a longitudinal direction viewing FIG. 2A of thedrawings. The end of shaft 68 opposite to that to which plate 54 andplate 62 are secured, is received within a valve housing 68, the valvehousing extending into the air chamber 24 in the manner illustrated andcooperating with sealing ring 32 whereby to close one end of the airchamber 24.

Air chamber 24 carries therewithin a rated coil spring 70 which, forpurposes of illustration, will be defined as being rated at poundspressure, although a spring of any suitable rating may be utilized,depending upon the pressure of the fluid delivered into the gun 10.

One end of spring 70 bears against a flange 72 provided as a part ofvalve housing 68, the opposite end of spring 70 hearing against thebottom wall 74 of reciprocable cup-shaped piston 28. As previouslydescribed, the casing 26 encloses piston 28 and'spring 70, said casing26 being configured in such a manner that there is provided an annularshoulder 76 adjacent one end thereof, which shoulder 76 is disposedinteriorly of air chamber 24 and serves as a stop for piston 28 as thesame moves to the left or toward the rear of the gun.

Disposed within the confines of casing 26 and closing the forward end ofthe air chamber 24, viewing FIGS. 2A and 4A, is a flexible diaphragm 78which overlies the bottom wall 74 of piston 28. A disc. 81) alsooverlies bottom wall 74 of piston 28, the disc 88 being secured to thepiston as shown in FIG. 2A and serving to clamp the diaphragm 78 betweenthe bottom wall 74 of piston 28 and the disc 89, the peripheral edge ofthe diaphragm 78 being suitably secured to the interior wall of casing26 by a sleeve 81.

Disposed forwardly of diaphragm 78, its holding disc 80, and sleeve 81,is toggle assembly 36 which is fixed in place within the housing 14, theassembly 36 including a toggle frame 82, the frame 82 pivotally carryinga pair of pawls 84 under pressure from a spring 85, the pawls 84 beingurged into engagement with an actuating shaft 86 coupled with andoperated by a'trigger shaft 87. Trigger shaft 87 extends inwardly intohousing 14 from the normally uppermost end of trigger 16, and a seal,broadly designated as 88, surrounds said shaft 87 at its point ofentrance into the housing 14 whereby to prevent the loss of fluid fromthe housing 14 around said shaft 87.

Actuating shaft 86 carries a plunger 90 and also has formed thereon, forcooperation with pawls 84, a pair of opposed, beveled rings 94 whichdefine a central ditch 96 which is engaged by the apex portion of thepawls 84, the same being urged thereinto by the spring 85. Shaft 8-6, tothe rear of rings 94, passes through toggle frame 82 and is surroundedby a washer 98, the shaft 86 cooperating with said washer 98 in themanner hereinafter described to selectively prevent and allow the flowof fluid past the portion of shaft 86 surrounded by Washer 98 and into asecondary chamber within air chamber 24, as will be hereinafterexplained.

The peripheral edge of plunger 90 has a notch 18% formed therein, thenotch 100 embracing valve rod 48,

there being a loose fit between said rod 40 and the notch 189 forpurposes hereinafter described. A stop rod 102 is supported by toggleframe 82 and extends toward rod 4 the rod 182 being engaged by a disc104 secured to the innermost end of rod 40 when the gun is under certainconditions of operation. Rod 40 extends along the length of barrel 38and outlet spout 18, the rod 40 being surrounded intermediate its endsby a coil spring 105, best shown in FIG. 2A of the drawings, one end ofcoil spring 106 resting against a sleeve 108 which is aflixed to rod 48,and the other end of the spring 186 resting against a threaded portionof the coupling which secures the spout 18 to the barrel 38. Rod 48carries, at the end thereof opposite to disc 184, a valve member 110,which valve member 118'is movable into and out of engagement with a seat112 formed adjacent the outlet aperture 114 of delivery spout 18, itbeing apparent that the rod 48 is reciprocable in a longitudinal path.

Gun 10 also carries adjusting mechanism 116 for controlling the amountof fluid which passes therethrough in a given dosage, this adjustingmechanism taking the form of a needle valve 118 adjustable by a screw120 with respect to a seat 122, the operation of adjusting mechanismbeing hereinafter more fully detailed.

Trigger 16 is'pivotally secured to housing 14 by means of a pin 124 andis normally urged to a closed position or to the right, viewing F165. 2Aand 4A, by means of a spring 125 suitably secured thereto and bearingagainst a portion of the housing 14.

The major components of the fluid dispensing gun 10 having beenhereinabove described, the operation of said gun will now be explained.

Fluid enters gun 10 by line 12, said fluid being under a preselectedpressure delivered by an outside source, this pressure being defined as40 pounds per square inch for purposes of illustration. The fluid entersgun 16 through port 22 and passage 20 and subsequently fills the entiremain chamber 34 of the gun 10. To accomplish this result, fluidinitially enters an annular portion 128 of chamber 34 and a given amountthereof passes through a passage portion 130 into a centrally disposedportion 132 surrounding the valve 58, the fiuid then continuing to fillchamber 34 by moving along passage 134 which surrounds that portion ofshaft 60 disposed rearwardly of ring 64, the fluid then moving into aportion 136 of chamber 34 and acting against the diaphragm 46.

The fluid then moves from portion 136 of the chamber 34 through alongitudinal passage portion 138 and into the main portion of chamber34, that is the portion most immediately surrounding casing 26. Itshould be noted that fluid enters said main portion of the chamber 34not only through passage 138 after following the route abovedescribed,but also initially enters said main portion under its introductionpressure through a bleed hole 140 which places the main portion ofchamber 34 into communication with portion 128.

The fluid entering through passage portion 138 and hole 140 passes alongthe main portion of chamber 34 and moves into portion 142 thereof whichis adjacent toggle assembly 36 and plunger 90, the fluid then movingalong a passage portion 144 which surrounds that portion of shaft 86between washer 98 and rings 94. Fluid then enters a secondaryfluid-receiving chamber 146 within air chamber 24, chamber 146 beingdefined by the toggle frame 82 on one end, and the diaphragm 78 on theother, sleeve 81 forming the side wall thereof, there being a sealingring 147 between frame 82 and sleeve 81, the fluid entering said chamber146 by moving along a passage 148 defined by washer 98 whereby to bringthe diaphragm 78 and piston 28 under the pressure of 40 pounds.

Fluid also moves along the barrel 38 and spout 18 of the gun 10 insurrounding relationship to rod 40, the fluid filling the outlet spout18 until such time as further forward flow thereof in chamber 34 isprevented by valve member 110 which is in the position shown in FIG. 2B.

of the drawings as the gun is being filled as above de scribed.

As the main chamber 34 fills with fluid as detailed hereinabove,secondary chamber 14-6 is also filled, whereby pressure is exertedagainst diaphragm 78 causing the same to flex and thereby move from theposition shown in FIG. 2A of the drawings to the position shown in FIG.4A of the drawings. As the diaphragm 78 is so flexed, piston 28 ispushed rearwardly in chamber 24 thus compressing the air within chamber24 and also compressing the coil spring 70 which, as heretoforeindicated, is rated at a pressure less than that under which the fluidis introduced into the gun and into chamber 146, the figure of 40 poundspressure being given as illustrative of the fluid pressure and thefigure of pounds being chosen in connection with the rated spring 70.

When the fluid has progressed to the point above described, the gun isin what may be termed a ready con dition, it also being noted that asthe fluid enters the main chamber 34 in the manner above described, thediaphragm 46 is flexed to the left as the pressure builds thereuponwhereby to compress the coil spring 50 when the pressure againstdiaphragm 4d has become sutficient to overcome the tension pressure ofspring 50, the valve 58 thereby being closed by moving ring 64 intoengagement with shoulder 66, it being apparent that upon the closing ofvalve 58, the rate of which closing is controlled by spring 50, the onlyroute by which fluid may enter the main portion of chamber 34 is fromportion 128 through bleed hole 140. Valve 58 is shown as open in FIG. 2Aof the drawings, but as closed in FIG. 4A of the drawings, the saidFIGURE 2A illustrating the gun immediately prior to receiving the fluidunder pressure, and FIG. 4A illustrating the gun at the moment thetrigger has been pulled to commence delivery of the fluid from the gunafter it has been filled as above described.

With the gun filled, the trigger 16 is manually actuated by swinging thesame about pin 124- in a clockwise direction viewing FIG. 4A of thedrawings, said trigger acting through its trigger shaft 87 to pushplunger 90 to the left or rear, viewing FIG. 4A, the movement of theplunger 9G and its associated components being aided by spring 195 whichurges sleeve 108 against plunger 90, said sleeve 108 being secured torod 40, the urging movement of spring 106 also serving to shift rod 40to the left when the plunger is pushed in said direction under urging byshaft 87. At approximately the same moment that rearward movement of rod40 is stopped as a result of disc 1G4 engaging stop in 102, pawls 84reach an over-center position and, as a result of their engagement withditch 96, hurry actuating shaft 86 to the left under the continuedpushing of trigger shaft 87 against plunger 99.

As shaft 86 moves to the left, a shoulder 152 formed thereon seats onwasher 8 whereby to prevent the further flow of fluid through passage148 and into secondary chamber 146. As rod 40 is moved to the left, asabove described, valve member 116 is moved away from seat 112 to an opencondition shown in FIG. 4B of the drawings, whereby passage of the fluidout of the aperture 114- of spout 18 and into the material to befumigated is permitted.

As fluid passes out of aperture 114, the pressure of the fluid withinthe gun is reduced, the reduction of pressure within the main chamber 34as a result of fluid flowing therefrom, causing the reduction ofpressure upon diaphragm 46 whereby the valve 58, which has been closed,is carried to the right under the urging of spring 50, moving the sameto an open condition, the extent of its opening being controlled by therate of flow of the fluid from the gun, said rate of flow beingdetermined by the diameter of aperture 114 and the size of passageportion 138 and bleed hole 146 As valve 58 opens, it allows a continuousflow of fluid through the gun under approximately 6 to 7 poundspressure, this pressure being achieved and regulated by the balancebetween spring 50 and the pressure of the fluid within the gun, valve 53functioning to reduce the pressure of incoming fluid from 40 pounds to 6or 7 pounds.

The extent of movement of the valve 58 is controlled by adjustment screw52, said screw being normally set in such a manner that the valve 58will allow the fluid entering the main portion of chamber 34 throughportion 136 and passage portion 138, to be under a pressure ofapproximately 6 or 7 pounds. Said pressure is maintained by theregulator assembly during delivery of fluid from the gun inasmuch ashole 140 is not of a size to alone allow a suflicient flow of fluidunder 40 pounds pressure into the main portion of chamber 34 to alterthe controlled pressure achieved by the regulator assembly.

As the pressure within the gun 10 is reduced during the delivery offluid therefrom, a reduction in pressure of the fluid within secondarychamber 146 is achieved, fluid being allowed to leave chamber 146, at acontrolled rate, through a passage 154 formed in toggle frame 82. Therate of flow of fluid through said passage 154 is controlled by needlevalve 122 which is interposed within said passage, said valve 122 beingadjustable by screw 120, all as is apparent from FIG. 5 of the drawings.A passage 156, in communication with passage 154, allows the fluidleaving chamber 146 to return to main chamber 34 for subsequentexpulsion from the gun 10.

As the pressure in chamber 146 is reduced to below 20 pounds, the ratingof spring 70, said spring 70 urges piston 28 and diaphragm 78 to theright from the position shown in FIG. 4A to return the same to theposition shown in FIG. 2A. As a result of such movement, plate 80 isbrought into engagement with the rearmost end of the actuating shaft 86whereby to urge shaft 86 and the plunger 90 forward or to the right,such movement being hurried by the action of pawls 84 within ditch 96.As the plunger 90 is so moved, the portion thereof adjacent notch 10%)re-engages sleeve 108, thereby pushing rod 48 to the right and seatingvalve member upon seat 112 whereby to close aperture 114 and terminatethe flow of fluid from the gun.

As is apparent, the period of time which aperture 114 remains open and,therefore, the dosage of fumigant delivered by gun 10, is controlled bythe speed of movement of piston 28 to a position actuating the shaft 86whereby to cause the valve closing movements above described. In turn,the speed of such movement of piston 28 is directly controlled byassembly 116 and particularly the needle valve 122 which controls therate of flow of fluid from the secondary chamber 146. Thus, it will beappreciated that the dosage delivered by gun 10 is under the directcontrol of the operator thereof who can readily adjust such dosagethrough rotation of screw 120, it not being necessary to adjust thedosage at a position remote from the gun 10.

Once the components of the gun 10 have moved to the position abovedescribed and the flow of fluid has thereby been terminated, the cycleof operation is again commenced, fluid pressure being allowed to buildup within the chambers whereby when the trigger is again actuated, thegun operates to repeat the steps above set forth and deliver, under acontrolled pressure, a measured dosage of fumigant fluid.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent is:

l. A fluid dispensing gun comprising a chamber for receiving fluid underpressure; means for regulating the pressure of the fluid delivered tosaid chamber; an air chamber formed within said fluid chamber; adiaphragm separating one end of said air chamber from said fluidchamber, said diaphragm being flexible whereby to define a secondaryfluid filled chamber when fluid is delivered to the gun; an actuatingshaft carried by said gun; a fluid delivery spout in communication withsaid fluid chamber; a valve for said spout, said valve being controlledby the movement of said actuating shaft; a trigger shaft for moving saidactuating shaft in-one direction, said diaphragm moving the actuatingshaft in the other direction and mechanism for predetermining the dosageof fluid which will' be dispensed by the gun upon the actuation thereof.

2. A fluid dispensing gun as set forth in claim 1, there being a pistoninsaid air chamber and in engagement with said diaphragm and a springfor said piston whereby to urge the same against the diaphragm.

3. A fluid dispensing gun as set forth in claim 2, there being a plungercarried by said actuating shaft; a rod carrying the valve for the spout;and a sleeve aflixed to said rod, said plunger engaging said sleevewhereby upon movement of the shaft in one direction the spout is allowedto open, and upon movement of the shaft in the other direction the spoutis closed.

4. A fluid dispensing gun as set forth in claim 3, there being a toggleassembly within the fluid chamber and acting upon said actuating shaftwhereby to aid in the movement thereof in said directionsj 5. A fluiddispensing gun comprising a chamber for receiving fluid under pressure;a diaphragm closing one end of said chamber; a fluid delivery spout incommunication With said chamber; a valve normally closing said spout andthereby the other end of said chamber; a closure member for said gun,said member cooperating with said diaphragm to define an atmospheric airchamber at one end of the'gun; a spring within said atmospheric airchamber and bearing against one face of said diaphragm, the fluid withinthe fluid-receiving chamber bearing against the other face ofsaiddiaphragm; a valve carried by said diaphragm and extending into saidfluid-receiving chamber whereby to control the flow of fluid into saidchamher; means for opening the valve in the fluid delivery spout toallow the flow of fluid out of the chamber through the spout; andmechanism forpredetermining the dosage of fluid which will be dispensedby the gun upon the actuation thereof.

6. A fluid dispensing gun comprising an outer housing; an inner casing;a chamber defined by said housing and said casing for receiving fluidunder pressure; anair chamber defined primarily by said casing; adiaphragm separating one end of said air chamber from said fluidchamber; a spring within said air chamber for normally urging saiddiaphragm in one direction; a fluid delivery spout in communication withsaid fluid chamber; a valve for said spout; means for regulating thepressure of the fluid within the gun; and actuating means for openingsaid valve of the fluid delivery spout to allow flow of a predetermineddosage of fluid from the gun, the amount of such dosage being determinedby the rate of movement of said diaphragm under the urging of saidspring.

7. A dispensing gun as set forth in claim 6, there being a valve in saidchamber for controlling the rate of movement of said diaphragm under theurging of said spring.

References Cited by the Examiner UNITED STATES PATENTS 2,402,036 6/46Giger 14l225 2,809,665 10/57 Crowe 138--30 2,818,890 1/58 Ryan 141-2252,902,988 9/59 Rippingille 138-30X 3,013,696 12/61 Tralmer 22256 EVERETTW. KlRBY, Primary Examiner.

LOUIS I. DEMBO, RAPHAEL M. LUPO, Examiners.

1. A FLUID DISPENSING GUN COMPRISING A CHAMBER FOR RECEIVING FLUID UNDERPRESSURE; MEANS FOR REGULATING THE PRESSURE OF THE FLUID DELIVERED TOSAID CHAMBER; AN AIR CHAMBER FORMED WITHIN SAID FLUID CHAMBER; ADIAPHRAGM SEPARATING ONE END OF SAID AIR CHAMBER FROM SAID FLUIDCHAMBER, SAID DIAPHRAGM BEING FLEXIBLE WHEREBY TO DEFINE A SECONDARYFLUID FILLED CHAMBER WHEN FLUID IS DELIVERED TO THE GUN; AN ACTUATINGSHAFT CARRIED BY SAID GUN; A FLUID DELIVERY SPOUT IN COMMUNICATION WITHSAID FLUID CHAMBER; A VALVE FOR SAID SPOUT, SAID VALVE BEING CONTROLLEDBY THE MOVEMENT OF SAID ACTUATING SHAFT; A TRIGGER SHAFT FOR MOVING SAIDACTUATING SHAFT IN ONE DIRECTION, SAID DIAPHRAGM MOVING THE ACTUATINGSHAFT IN THE OTHER DIRECTION AND MECHANISM FOR PREDETERMING THE DOSAGEOF FLUID WHICH WILL BE DISPENSED BY THE GUN UPON THE ACTUATION THEREOF.